Calculating-scale.



No. 746,889. PATENTBD DEG. 15, 1903.

R. C. SMITH. l GALGULATING SCALE.

APPLICATION FILED SEPT. 12. 1903.

N0 MODEL.

l i. il n IVI /NVENTOH ATTORNEY UNITED STATES Patented December 15,1903.

RUDOLPH C. SMITH, OF YONKERS, NEW YORK.

CALCULATlNG-SCALE.

SPECIFICATION forming part of Letters Patent No. 746,889, dated December15, 1903.

Application filed September 12, 1903. Serial No. 172,881. (No model.)

To all whom it' may concern,.-

Be it known that I, RUDOLPH C. SMITH, a citizen of the United States,and a resident of Yonkers, in the county of Westchester and State of NewYork, have invented certain new and useful Improvements in Calculating-Scales,of which the followingisaspecification.

The object of my invention is to construct an instrument which will inevery case register mechanically the correct decimal value of the firstfigures of numbers used in the 0peration of a logarithmic scale forcalculations. Such an instrument, as is Well known, is of the greatestutility, as it does away with the many chances of error caused by thenecessity of constant mental attention While using the ordinary slide.In a pending application, Serial No. 1,105, led by me on January 11,1900, I have described a construction for this purpose where the use ofthree scales on one slide, different by a multiple of ten, enables eachof the three to register, respectively, a tenfold greater value than theone preceding it.

My present invention consists in the construction of a cursor which, inconjunction with uniformly-spaced divisions on the slide and stationarypart of a slide-rule with decimal figures and with directive means onthe ordinary logarithmic scale, will obtain the same result as isreached with the three auxiliary scales of my other pending application.

Figure 1 is a top plan view of a calculating-scale embodying myinvention. Fig. 2 is a plan showing the under side of same. Fig. 3 is alongitudinal side elevation of same; and Figs. 4 and 5 are respectivelyend elevations of the same, looking at the right-hand ends of Figs. 1and 2, respectively.

The arrangement ofthe ordinary logarithmically-spaced slide-rule is wellknown and needs no detailed description. It consists of a stationarypart and of a slidable part which can be moved to the desired place onthe stationary part in proper guides. I prefer to use the constructiondescribed in my Patent No. 592,067, dated October 19, 1897, where theslide is held and guided by the celluloid flexible transparent cover orplate.

The main slide 1 is held in place and slides on the stationary stock orpart 4 below a flexible transparent covering-plate 2,which is kept atits proper place and at proper clearance for the slide 1 by the rivets3, the latter being small strips of metal passing through the plate 2and stock 4 and having their ends bent at right angles to form heads, asshown in Fig. 5. The slide 1 as well as the stationary part 4 areprovided with any of the well-known logarithmic Gunter scales; but in myimproved instrument the scales on the slide 1 as well as those on thestock 4 are prominently marked with a visible sign in such a way thatthe same sign, in conjunction with the cursor and the decimal spaces ofthe slide, is used to register the correct (leci-V nial value of theresults obtained, as will be explained hereinafter.

The cursor 6 may be the ordinary cursor used with this class ofinstruments; but the cursor 5 is provided with three indexes 17, 20, and19, respectively, coinciding with the spacing of the decimal figures onthe slide 8 by which the decimals are registered. The index-line 2O ofthe cursor 5 extends in a continuous line all around the stationary part4, so as to serve to register the spacing on the back of the instrumentwith the middle line 2O of the said three indexes at the front of thecursor.

The figures on the auxiliary slide 8 and on the stationary part 7 of thedecimal-scale are in three rows, which contain, respectively, thedecimals of the rows of figures on the main scale, which are marked 3,4,7 1, and 2, (not as numerals of reference, but as incorporated withthe instrument,) as shown at the left-hand end of Fig. 1.

It will be noticed that the upper row of the stationary scales are thesquare roots of the lower row of figures, while the slides have the samerow of figures as the lower row of ligures on the stationary parts.

For the purpose of distinguishing the figures of the left half of theinstrument from those of' the right half and for the purpose of iixingthe figures to be registered with the proper index of the cursor 5 Iprovide the stationary sleeve 10 in the middle of the stationary part 4of the main scale, through which sleeve 10 the main slide 1 slides.Heavy red lines 11 12, respectively, inclose the ligures of the left ofthe main slide 1 and of the stationary part 4. The upper and lower redIOO lines 12 of the stationary part 4 form, so to speak, a frame withthe fixed cursor 10, and the red lines 11 join on across-line 13, whichforms the end of the left half of the slide 1.

I provide the cursor 5 between the index 17 and index-opening 16 withthe same transparent color, red, as used for the lines 11 and 12 on theleft half of the instrument, while the surface of the slide S to theright of the index 19 (notbeing under the said transparent color)appears as white, which is the color of the right half of the mainscale. I have discovered that this construction of the instrument iscapable of registering the decimal mechanically, following a very simplerule of operation, viz: Repeat every move of the cursor 6 and slide 1 ofthe main scale with the cursor 5 and slide 8 of the decimal-scale, usingthe numbers on the main scale and the decimal of their first figures onthe decimal-slide. Read all decimals in line with the middle index 20 ofthe cursor 5, except those of fractions where numerator and divisor havedifferent colors. In this case the numerator is taken with the red index17 of the cursor if it is on the red left half of the main rule and withthe index 19 to the right of the middle opening 16 when the numerator ison the white half of the main slide.

The instrument registers factors of proper and improper fractions, like60 X 2 X 600 answer answer 3 5 E s 15 by the following sequence of movesfor all the fractions: Fix the divisor (in our example 3) on the mainslide 1 with the ordinary cursor 6. Repeat the same operation, using thedecimal 1 of the divisor 3in our example and the special cursor 5 of thedecimal auxiliary silde 8, moving the cursor 5 until the decimal 1 onthe slide S is within the opening16 and coinciding with index 20. Nowmove the main slide 1 to bring the numerator 60 to the positionpreviously fixed for the denominator by the cursor 6 in the firstoperation above explained. Repeat the same move with the slide 8 of thedecimal-scale, using the decimal of the first figure of thenumerator,-which is 10 in this case, and moving said slide S until the10 on the slide appears in the aforesaid opening 16 of cursor 5, whichis the position of the parts shown in Fig. 1.

Read all values of decimals in line with index-line 20, except when thenumerator and divisor are of dierent colors, then use a red numeratorwith the index 17 to the left of the opening 16, while with a whitenumerator on a red denominator the index 19 to the right of the opening16 should be used.

Fig. lshows the position of the scale after the numerator 60 has beenmoved to the edge of the cursor 6, (the latter being in the position inwhich it previously fixed the 3 and also the position of the cursor 5 onthe decimal-scale, (both terms in this illustration being of the samered color,) with 10 in the opening 16 of the cursor 5, in line with 1 onthe stationary part 7 of the decimal-scale. The next move will be themain cursor 6 to 5 on the slide 1 and the opening 16 of the cursor 5 tothe 1 on the slide 8. Then move the main slide 1 until the 2 thereonreaches the edge of the main cursor 6, and leave the opening 16 ofcursor 5 on the 1 of the decimal-slide, since the decimal of the 2 and 3composing the fractions is 1 and since they both are of the same color.Now move edge of main cursor 6 to 12 on slide 1 and move opening 16 ofdecimal-cursor 5 to the 10 on the decimal-slide S, then move slide 1until the 600 thereon reaches the position xed for the denominator 12 bythe cursor 6 in the previous move, and then move the slide 8 until the100 thereon is directly below the red index 17 of cursor 5, since thedenominator 12 was white and the numerator 600 was red. Above the 3found on the stock 4- read answer 32 on slide 1. Both being red, read inopening 16 of decimal-cursor 1000 as the decimal of the first figure ofsaid 32, giving the answer, consequently, as 3200. If multiplying withiifteen instead of by eight, move the cursor 5 until index-line 20thereof coincides with the 10 on part 7, then above 15 on stock 4 wefind 6 on slide 1 as the first figure of the answer, and then we find1000 as the decimal of the answer in line with red index 17 of cursor 5,thus disclosing the final answer as 6000.

Without limiting myself to the precise construction and arrangementshown, I claim as my invention- 1. A sliding rule having lines ofuniform spacing, marked respectively with a ccntinuous series of powersof ten, with a cursor having three indexes of the same spacing; as andfor the purpose described.

2. In combination with the logarithmic slide-rule, an auxiliaryslide-rule with scales of uniform spacing, marked with a continuousseries of powers of ten,and with the cursor having three indexes of thesame spacing as the scales of the auxiliary slide-rule; substantially asset forth.

3. In combination with the logarithmic slide-rule, an auxiliaryslide-rule of uniform spacing, and marked with a continuous series ofpowers of ten, and with a cursor having three indexes of the samespacing and ren spectively the same distinguishing-sign which appears onthe halves of the logarithmic slide; substantially as described.

4. In combination with the logarithmic slide-rule, an auxiliaryslide-rule of uniform spacing, and marked with the series of powers often, with the cursor having three indexes of the same spacing andrespectively with same distinguishing-sign which appears on the halvesof the logarithmic slide, and with the stationary sleeve of thelogarithmic scale; substantially as described.

5. In combination with the logarithmic slide-rule, an auxiliaryslide-rule of uniform.

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spacing, marked with the continuous series of powers of ten, with thecursor having,r three indexes of the same spacing and the samedistinguishing-sign which appears on the logarithmic slide, and with itsmiddle index extending around the front and back of the instrument;substantially as described.

Signed at New York, in the county of New York and State of New York,this 11th day of September, A. D. 1903.

RUDOLPH C. SMITH.

Witnesses:

GRAS. C. GILL, ARTHUR MARION.

